This disclosure pertains to a Ross corrected Cassegrain-like telescope operating in a wide range of wavelengths.
Cassegrain-like telescopes including the classic Cassegrain telescope, the Dall-Kirkham telescope, the Schmidt-Cassegrain telescope, the Maksutov-Cassegrain telescope, the Argunov-Cassegrain telescope, the Klevtsov-Cassegrain telescope, and the Ritchey-Chretien (RC) telescope are widely used for observation of objects in the visible wavelength range. Cassegrain-like two-mirror based telescopes are known to have a very limited field of view (FOV), limited by off-axis field curvature, as well as coma and astigmatism. The RC telescope is designed to eliminate coma and provide a larger field of view than the Cassegrain configuration. The classic Cassegrain telescope has a primary parabolic mirror and a secondary hyperbolic mirror. The RC telescope has a hyperbolic primary and a hyperbolic secondary mirror.
Correction of off-axis aberrations in a Cassegrain-like two-mirror telescope has been implemented using Ross or Wynne optical aberrations correctors. Ross and Wynne optical aberration correctors use a series of field lenses that are located near the final image formed by the Cassegrain-like two-mirror based telescope. However, conventional Ross or Wynne optical correctors exclusively used optical glass lenses and are operated in the visible wavelength range. Optical glass lenses have a limited range of wavelength operation and, in particular, are not suitable for a broader wavelength range, such as a wavelength range between about 0.4 μm and about 12 μm.
Therefore, there is a need in the art for a Cassegrain-like telescope, such as an RC telescope, that uses optical aberration correctors that can operate in the wavelength range between about 0.4 μm and about 12 μm which includes the short wavelength infrared (SWIR) range (between about 1.4 μm and about 3 μm), the mid-wavelength infrared (MWIR) range (between about 3 μm and about 8 μm) and at least a portion of the long-wavelength infrared (LWIR) range (between about 8 μm and about 15 μm) while providing an extended field of view (FOV) equal to or greater than about 1 deg.